Tree functional diversity affects litter decomposition and arthropod community composition in a tropical forest

Disturbance can alter tree species and functional diversity in tropical forests, which in turn could affect carbon and nutrient cycling via the decomposition of plant litter. However, the influence of tropical tree diversity on forest floor organisms and the processes they mediate are far from clear. We investigated the influence of different litter mixtures on arthropod communities and decomposition processes in a 60‐year‐old lowland tropical forest in Panama, Central America. We used litter mixtures representing pioneer and old growth tree species in experimental mesocosms to assess the links between litter types, decomposition rates, and litter arthropod communities. Overall, pioneer species litter decomposed most rapidly and old growth species litter decomposed the slowest but there were clear non‐additive effects of litter mixtures containing both functional groups. We observed distinct arthropod communities in different litter mixtures at 6 mo, with greater arthropod diversity and abundance in litter from old growth forest species. By comparing the decay of different litter mixtures in mesocosms and conventional litterbags, we demonstrated that our mesocosms represent an effective approach to link studies of litter decomposition and arthropod communities. Our results indicate that changes in the functional diversity of litter could have wider implications for arthropod communities and ecosystem functioning in tropical forests.     

The role of cladocerans in tracking long-term change in shallow lake trophic status

Shallow lakes have been affected by a variety of human activities profoundly altering their ecological structure and function. Cladocerans have been used to track change resulting from a variety of drivers at a number of time scales. Aquatic macrophytes are well recognised as reflecting the ecological condition of a lake. Here, we compare the plant macrofossils with the sub-fossil cladoceran assemblages from 20 dated sediment cores. Co-correspondence analysis was used to determine the degree of commonality of change in community composition of the two biological groups through time. This analysis revealed very high levels of agreement in the nature and timing of change at all the sites examined with very high correlation coefficients between the axis 1 scores for macrofossils and cladocerans. Furthermore, at all sites a high proportion of the variance (min 20%, max 54%) in the macrofossil data was explained by the change in the cladoceran assemblage. Sub-fossil macrofossil and cladoceran assemblages, from at least from 1700 AD onwards, were examined in more detail at three sites: Ormesby Great Broad, Felbrigg Lake and Lake Søbygaard. There was very good accord in the main shifts of the cladoceran and macrofossil assemblages at all three sites. This may reflect the long-term shift in the principal focus of primary production from the benthic to the pelagic habitat. We suggest that the combination of their central position in the food-web and the presence of both pelagic and benthic taxa make cladocerans a strong candidate as the single best indicator of (palaeo) ecological condition related to changing trophic status and alteration in food-web structure in shallow lakes.     

Towards the conservation of crucian carp Carassius carassius: understanding the extent and causes of decline within part of its native English range

The extent and causes of crucian carp Carassius carassius decline were assessed during an initial study of c. 25 ponds in north Norfolk, eastern England, U.K., which was then replicated (a validation study) on another c. 25 ponds in an adjacent area. Of these ponds, c. 40 are known to have contained C. carassius during the 1970s-1980s. In the initial and validation studies, C. carassius were found in only 11 of these ponds, yielding declines of 76% (five of 21 ponds) and 68% (six of 19 ponds), respectively (72% decline overall). Non-native cyprinids, including goldfish Carassius auratus and common carp Cyprinus carpio and their hybrids with C. carassius, were observed in 20% of the ponds. Causes of C. carassius local extinction from 21 ponds were confidently determined as desiccation due to drought, terrestrialization and habitat deterioration, hybridization and competition with non-native cyprinids, agricultural land reclamation and predation (after the introduction of pike Esox lucius). This study led to C. carassius being designated as a Biodiversity Action Plan (BAP) species in the county of Norfolk, the first formal conservation designation for the species in the U.K. The C. carassius BAP plan aims to halt the decline of this much overlooked species through reintroductions and selective stocking of suitable ponds within the native range of the species.     

Representation of aquatic vegetation change by plant macrofossils in a small and shallow freshwater lake

We explored spatial and temporal relationships between contemporary aquatic vegetation and surface sediment macrofossil remains in a small, shallow, English lake (Green Plantation Pond). The aquatic vegetation of Green Plantation Pond underwent a marked compositional change after 2005 with a shift from Elodea spp.-Potamogeton pusillus-Chara spp. to Ceratophyllum spp.-Chara spp.-Potamogeton crispus dominance. By comparing macrophyte and plant macrofossil distributions at multiple, closely spaced points in Green Plantation Pond for 2000 and 2008–2009, we studied the ability of macrofossils to track this major aquatic vegetation change. Representation of macrophytes by macrofossils was high with 63 and 76 % of extant plant species recorded by macro-remains in the 2000 and 2009 sediment surveys respectively. Nevertheless, plants were both over-represented (Nitella flexilis, Chara spp. and Zannichellia palustris) and under-represented (Ranunculus sect. Batrachium, Potamogeton spp.) in the sediment record in terms of relative macrofossil abundances and the number of occupied sample points. The study also revealed a lack of preservation of Elodea spp. leaf remains in the second (2009) survey compared to the first (2000) probably due to a longer time interval (5 vs. 10 months) between macrophyte and sediment sampling. Nevertheless, the macrofossils reliably recorded both the main shift in the contemporary vegetation (e.g. especially increases in Ceratophyllum spp. and P. crispus abundance) and other more subtle floristic changes (e.g. increases in Myriophyllum spicatum and Lemna spp.) exceptionally well. This study highlights the huge potential of macrofossils for tracking sub-decadal changes in the aquatic vegetation of small, shallow lakes.     

Cytokine profiles in the joint depend on pathology,but are different between synovial fluid,cartilage tissue and cultured chondrocytes

Introduction

This study aimed to evaluate whether profiles of several soluble mediators in synovial fluid and cartilage tissue are pathology-dependent and how their production is related to in vitro tissue formation by chondrocytes from diseased and healthy tissue.

Methods

Samples were obtained from donors without joint pathology (n = 39), with focal defects (n = 65) and osteoarthritis (n = 61). A multiplex bead assay (Luminex) was performed measuring up to 21 cytokines: Interleukin (IL)-1α, IL-1β, IL-1RA, IL-4, IL-6, IL-6Rα, IL-7, IL-8, IL-10, IL-13, tumor necrosis factor (TNF)α, Interferon (IFN)γ, oncostatin M (OSM), leukemia inhibitory factor (LIF), adiponectin, leptin, monocyte chemotactic factor (MCP)1, RANTES, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), vascular growth factor (VEGF).

Results

In synovial fluid of patients with cartilage pathology, IL-6, IL-13, IFNγ and OSM levels were higher than in donors without joint pathology (P ≤0.001). IL-13, IFNγ and OSM were also different between donors with cartilage defects and OA (P <0.05). In cartilage tissue from debrided defects, VEGF was higher than in non-pathological or osteoarthritic joints (P ≤0.001). IL-1α, IL-6, TNFα and OSM concentrations (in ng/ml) were markedly higher in cartilage tissue than in synovial fluid (P <0.01). Culture of chondrocytes generally led to a massive induction of most cytokines (P <0.001). Although the release of inflammatory cytokines was also here dependent on the pathological condition (P <0.001) the actual profiles were different from tissue or synovial fluid and between non-expanded and expanded chondrocytes. Cartilage formation was lower by healthy unexpanded chondrocytes than by osteoarthritic or defect chondrocytes.

Conclusions

Several pro-inflammatory, pro-angiogenic and pro-repair cytokines were elevated in joints with symptomatic cartilage defects and/or osteoarthritis, although different cytokines were elevated in synovial fluid compared to tissue or cells. Hence a clear molecular profile was evident dependent on disease status of the joint, which however changed in composition depending on the biological sample analysed. These alterations did not affect in vitro tissue formation with these chondrocytes, as this was at least as effective or even better compared to healthy chondrocytes.     

Sensitive fluorescence in situ hybridization signal detection in maize using directly labeled probes produced by high concentration DNA polymerase nick translation

The signal produced by fluorescence in situ hybridization (FISH) often is inconsistent among cells and sensitivity is low. Small DNA targets on the chromatin are difficult to detect. We report here an improved nick translation procedure for Texas red and Alexa Fluor 488 direct labeling of FISH probes. Brighter probes can be obtained by adding excess DNA polymerase I. Using such probes, a 30 kb yeast transgene, and the rp1, rp3 and zein multigene clusters were clearly detected.     

Growth, diet and condition of goldsinny on the west coast of Scotland

A study of seasonal, locational and sexual variations of growth, diet, somatic condition ( K _s), gonadosomatic condition (GSI) and hepatosomatic condition (HSI), of the goldsinny wrasse, Ctenolabrus rupestris , was made on specimens taken from three areas (Millport, Oban and Luing) of the west coast of Scotland from May 1992 to June 1993. Capture throughout the year was by either baited creel or by anaesthetics applied underwater. Male goldsinny of age 1 year and older ranged in total length from 67-155 mm, total weight 3.8-58.8 g, and had a maximum age of 14+ years. Females of 1 year and older ranged in total length from 59-159 mm, total weight 2.4-65.4 g and had a maximum age of 20+ years. Juvenile (0 +) goldsinny were mostly of indeterminate sex, ranged in total length from 16-57 mm, and total weight 0.08-1.97 g. Female growth was slower than that of males for all three locations; growth of male and female goldsinny from Millport was slower than the respective sexes at the other two locations. Length-weight relationships varied with age and location. There were differences in K _s, GSI, HSI and dietary trends associated with variation in season, sex and location. The implications of this variation are discussed in relation to the management of a sustainable goldsinny fishery.     

Distinct responses of soil respiration to experimental litter manipulation in temperate woodland and tropical forest

Global change is affecting primary productivity in forests worldwide, and this, in turn, will alter long‐term carbon (C) sequestration in wooded ecosystems. On one hand, increased primary productivity, for example, in response to elevated atmospheric carbon dioxide (CO₂), can result in greater inputs of organic matter to the soil, which could increase C sequestration belowground. On other hand, many of the interactions between plants and microorganisms that determine soil C dynamics are poorly characterized, and additional inputs of plant material, such as leaf litter, can result in the mineralization of soil organic matter, and the release of soil C as CO₂ during so‐called “priming effects”. Until now, very few studies made direct comparison of changes in soil C dynamics in response to altered plant inputs in different wooded ecosystems. We addressed this with a cross‐continental study with litter removal and addition treatments in a temperate woodland (Wytham Woods) and lowland tropical forest (Gigante forest) to compare the consequences of increased litterfall on soil respiration in two distinct wooded ecosystems. Mean soil respiration was almost twice as high at Gigante (5.0 μmol CO₂ m^?2 s^?1) than at Wytham (2.7 μmol CO₂ m^?2 s^?1) but surprisingly, litter manipulation treatments had a greater and more immediate effect on soil respiration at Wytham. We measured a 30% increase in soil respiration in response to litter addition treatments at Wytham, compared to a 10% increase at Gigante. Importantly, despite higher soil respiration rates at Gigante, priming effects were stronger and more consistent at Wytham. Our results suggest that in situ priming effects in wooded ecosystems track seasonality in litterfall and soil respiration but the amount of soil C released by priming is not proportional to rates of soil respiration. Instead, priming effects may be promoted by larger inputs of organic matter combined with slower turnover rates.     

Stereoselective formation of benzo(c)phenanthrene (+)-(3S,4R) and (+)-(5S,6R)-oxides by cytochrome P450c in a highly purified and reconstituted system

The principal oxidative metabolites formed from benzo(c)phenanthrene (B(c)Ph) by the cytochromes P450 in liver microsomes from control and treated rats are the 3,4- and 5,6-arene oxides. A procedure is described which allows determination of the enantiomer composition and absolute configuration of these arene oxides based on HPLC separation of isomeric thiolate adducts formed with N-acetyl-L-cysteine in base. Incubation of [3H]-B(c)Ph with highly purified cytochrome P450c in a reconstituted monooxygenase system followed by trapping of the metabolically formed arene oxides as above indicated that the 3,4-oxide was predominantly the (+)-(3S,4R)-enantiomer (90%) and that the 5,6-oxide consisted mainly of the (+)-(5S,6R)-enantiomer (76%). The results are discussed in terms of their implications about the catalytic binding site of cytochrome P450c.